Hey boys and girls, would I notice much of a difference in speed if I put my OS on my new 160GB (8MB cache) Maxtor, or would it not really make a difference?

I was thinking about only really using the 160GB for storage, but if it'll make much of a difference, I'll use it as my primary drive. And when I format, I guess I'll have to make due with only 80GB of backup space.